ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-8-7325-2008Contribution of very short-lived organic substances to stratospheric chlorine and bromine in the tropics – a case studyLaubeJ. C.12EngelA.1BönischH.1MöbiusT.1WortonD. R.24SturgesW. T.2GrunowK.3SchmidtU.11Institute for Atmosphere and Environment, University of Frankfurt, Germany2School of Environmental Sciences, University of East Anglia, UK3Institute for Meteorology, Free University of Berlin, Germany4now at: Department of Environmental Science, Policy and Management, University of California, Berkeley, USA1112200882373257334This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from http://www.atmos-chem-phys.net/8/7325/2008/acp-8-7325-2008.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/7325/2008/acp-8-7325-2008.pdf

The total stratospheric organic chlorine and bromine burden was derived from
balloon-borne measurements in the tropics (Teresina, Brazil, 5&deg;04´ S,
42&deg;52´ W) in 2005. Whole air samples were collected cryogenically at
altitudes between 15 and 34 km. For the first time, we report
measurements of a set of 28 chlorinated and brominated substances in the
tropical upper troposphere and stratosphere including ten substances with an
atmospheric lifetime of less than half a year. The substances were
quantified using pre-concentration techniques followed by Gas Chromatography
with Mass Spectrometric detection. In the tropical tropopause layer at
altitudes between 15 and 17 km we found 1.1–1.4% of the chlorine and
6–8% of the bromine to be present in the form of very short-lived
organic compounds. By combining the data with tropospheric reference data
and age of air observations the abundances of inorganic chlorine and bromine
(Cl<sub>y</sub> and Br<sub>y</sub>) were derived. At an altitude of 34 km we calculated
3062 ppt of Cl<sub>y</sub> and 17.5 ppt of Br<sub>y</sub> from the decomposition of both
long- and short-lived organic source gases. Furthermore we present
indications for the presence of additional organic brominated substances in
the tropical upper troposphere and stratosphere.